This application claims priority under 35 U.S.C. .sctn. 119 of European Patent Application No. 97201746.1, filed in the European Patent Office on Jun. 10, 1997.
The invention relates to a catheter system for rapid exchange via a guidewire with a flexible, elongated inner catheter, which has a proximal end and a distal end as well as a guidewire lumen, which extends from an insertion port on the distal end to a lateral through port distally from the proximal end, and a flexible, tubular outer catheter, inside which the inner catheter is disposed axially displaceably and which has a lateral exit port for the guidewire.
Catheter systems with two catheters disposed one inside the other and displaceable relative to each other have many potential uses in interventions in body cavities, such as in blood vessels, air passages, or the esophagus. Usually, the catheter system is inserted along a pre-positioned guidewire through a body lumen to the desired site for use there.
For example, U.S. Pat. No. 4,655,746 discloses a catheter system, in which the inner and outer catheters are designed as balloon catheters, such that a vascular segment bounded by the balloons may be sealed relative to the rest of the vascular system. The distance between the balloons and thus the length of the vascular segment to be sealed may be adjusted by shifting the outer catheter relative to the inner catheter. Via a lumen provided for this, a therapeutic substance is infused into the sealed vascular segment or fluid is aspirated therefrom. The guidewire lumen extends in this catheter system over the entire length of the inner catheter. A catheter exchange with an indwelling guidewire requires either a very long guidewire or the attachment of an extension. Either is very time-consuming and represents an additional strain on the patient. Moreover, a second person must assist during such an intervention, and a large area around the puncture opening must be kept sterile.
To overcome the aforementioned disadvantages, catheter systems have been developed in which the guidewire lumen extends over only a short distal portion, and the guidewire runs for most of its length beside the catheter system to the proximal end. The guidewire protrudes out of the body by only roughly the length of the guidewire lumen, whereby a rapid catheter exchange is possible without attachment of an extension.
From EP 0 505 686 B1, a catheter system of the type mentioned in the introduction is known, in which the inner catheter is designed as a rapidly exchangeable balloon catheter with a premounted stent, whereas the outer catheter serves as a protective sheath during insertion of the stent. The guidewire leaves the catheter system proximally through two mutually aligned ports in the inner and outer catheters. To insert the catheter system, the two ports are at least partially aligned such that the catheter system can move along the guide wide. To expand the stent, the outer catheter is retracted along the inner catheter, whereby the guidewire ports move against each other and the guidewire runs between the openings in an annular lumen between the inner and outer catheter. After successful stent implantation, the outer catheter, which has a slot for this purpose extending from the guidewire port to the distal end of the outer catheter, may first be retracted. Then, the balloon catheter is removed from the body in a known manner along the guidewire. In the manipulation of such a catheter system in the vascular system of a patient, for example, it is possible for the inner and outer catheters to twist against each other, particularly in the distal portion of the catheter system, whereby the mutual position of the guidewire ports changes. During insertion or withdrawal of the catheter system, this results in undesired clamping of the guidewire in the zone of the ports, which significantly hinders rapid and uniform movement of such a catheter system. In addition, the guidewire ports may lose their mutual alignment during displacement of the outer catheter along the inner catheter, and additional frictional forces between the guidewire and the rim of the port may have to be overcome. And finally, during retraction of the outer catheter, the guidewire may be pressed into the slot and become clamped there.
WO 94/15549 discloses a likewise rapidly exchangeable catheter system. A self-expanding stent, which is confined in its compressed state between an inner and an outer catheter on the distal end of the catheter system, is released by retracting the outer catheter relative to the inner catheter. The guidewire leaves the catheter system proximally through a lateral port in the inner catheter and a slot in the outer catheter. An elongated depression, in which the guidewire can lie during retraction of the outer catheter, connects proximally to the port in the inner catheter. Thus, the guidewire is gently guided out of the catheter system without sharp bending. The slot in the outer catheter is, however, so narrow that significant frictional forces occur during displacement of the catheter system along the guidewire, and also during retraction of the outer catheter. Moreover, the catheter system suffers from the disadvantage that the slot and the depression reduce the cross-section and thus the kink resistance of the catheter system, in particular when the slot and the depression extend to the proximal end of the catheter system.
All documents cited herein, including the foregoing, are incorporated herein by reference in their entireties for all purposes.